Pre-discovery observations of CoRoT-1b and CoRoT-2b with the BEST survey

TL;DR

This paper reports pre-discovery observations of CoRoT-1b and CoRoT-2b using the BEST survey, demonstrating the utility of archival ground-based data for early detection and confirmation of exoplanet transits.

Contribution

It presents the first detection of CoRoT-1b and CoRoT-2b transits in archival ground-based data, aiding early follow-up of space-based exoplanet candidates.

Findings

Detected transits of CoRoT-1b and CoRoT-2b in archival data

No period change observed over ~4 years

Archival data useful for early exoplanet confirmation

Abstract

The BEST wide-angle telescope installed at the Observatoire de Haute-Provence and operated in remote control from Berlin by the Institut fuer Planetenforschung, DLR, has observed the CoRoT target fields prior to the mission. The resulting archive of stellar photometric lightcurves is used to search for deep transit events announced during CoRoT's alarm-mode to aid in fast photometric confirmation of these events. The "initial run" field of CoRoT (IRa01) has been observed with BEST in November and December 2006 for 12 nights. The first "long run" field (LRc01) was observed from June to September 2005 for 35 nights. After standard CCD data reduction, aperture photometry has been performed using the ISIS image subtraction method. About 30,000 lightcurves were obtained in each field. Transits of the first detected planets by the CoRoT mission, CoRoT-1b and CoRoT-2b, were found in archived data of the BEST survey and their lightcurves are presented here. Such detections provide useful information at the early stage of the organization of follow-up observations of satellite alarm-mode planet candidates. In addition, no period change was found over ~4 years between the first BEST observation and last available transit observations.